5x2-10x-840=0

Solution for 5x2-10x-840=0 equation:

5x^2-10x-840=0

a = 5; b = -10; c = -840;
Δ = b2-4ac
Δ = -102-4·5·(-840)
Δ = 16900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16900}=130$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-130}{2*5}=\frac{-120}{10}
=-12
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+130}{2*5}=\frac{140}{10}
=14
$